Alumina-forming austenitic (AFA) steel with high creep strengths and excellent high-temperature corrosion resistance has a promising potential being applied to high-temperature components of ultra-supercritical power plants. The effect of Cu addition on microstructure and tensile properties of Fe–20Ni–14Cr alumina-forming austenitic (AFA) steel after aging at 973 K has been investigated using various morphology microscopic characterizations and tensile test. The obtained results show that Cu addition promotes the formation of nanoscale B2–NiAl phase in AFA steel, which further increases the tensile strength and ductility of the materials to 1464 MPa and ductility of 23.81%, respectively. By occupying Fe and Ni atoms locations in the nanoscale B2–NiAl phase of AFA steel, Cu atoms reduce the chemical driving force of the nanoscale B2–NiAl phase growth. Such phenomenon results in reduction of the corresponding phase formation energy, and thus improves the phase stability. The occupancy behavior of Cu and its effect on the particle size in nanoscale B2–NiAl phase were quantitatively evaluated by first-principle calculation. The present research work proves that the precipitation strengthening plays a dominant role in the yield strength improvement of AFA steel.

具有高蠕变强度和优异耐高温腐蚀性能的氧化铝成型奥氏体（AFA）钢在超超临界电厂的高温部件中具有广阔的应用前景。已经使用各种形貌微观表征和拉伸试验研究了添加 Cu 对 Fe-20Ni-14Cr 氧化铝形成奥氏体 (AFA) 钢在 973 K 时效后的显微组织和拉伸性能的影响。结果表明，Cu的添加促进了AFA钢中纳米级B2-NiAl相的形成，进一步提高了材料的抗拉强度和延展性，分别达到1464 MPa和23.81%。通过占据 AFA 钢纳米级 B2-NiAl 相中的 Fe 和 Ni 原子位置，Cu 原子降低了纳米级 B2-NiAl 相生长的化学驱动力。这种现象导致相应的相形成能降低，从而提高了相稳定性。通过第一性原理计算定量评估了 Cu 的占据行为及其对纳米级 B2-NiAl 相中粒径的影响。目前的研究工作证明，沉淀强化在AFA钢的屈服强度提高中起主导作用。